Anatomical variations of the anterior inferior cerebellar artery.

Background: Anterior inferior cerebellar artery (AICA) is one of the three major cerebellar arteries. Nevertheless, AICA may exhibit a wide range of variations in its origin site, degree of development, number, and its reciprocal relationship with neighboring vessels. These morphological variations have important anatomical and clinical implications. The aim of this study was to investigate the anatomical variations of the AICA based on computed tomography angiography, a modality frequently used in clinical practice.

Materials and methods: The study retrospectively analyzed the computed tomography angiography examinations of the head and neck performed consecutively on a cohort of 153 hemifaces that met the established inclusion criteria.

Results: Based on the results of the present study, a new classification system dividing AICA into six distinct types has been developed. Among these types, Type 1 (single AICA originates from the proximal part of the basilar artery) was the most prevalent, accounting for 57.5% of all cases. Type 2 (single AICA originates from the middle part of the basilar artery) was the next most common at 22.9%. The median diameter of the AICA at its origin was 2.10 mm, ranging from 1.14 mm to 2.88 mm, while its cross-sectional area ranged widely from 0.81 mm² to 4.59 mm², with a median of 2.52 mm². The diameter of the basilar artery at the AICA origin was notably larger, with a median of 4.41 mm and a maximum of 12.00 mm. Correlation analysis between measured parameters and patient age indicated generally weak and statistically non-significant correlations.

Conclusions: This study underscores the anatomical complexity and variability of the AICA, emphasizing the importance of precise morphological knowledge for both diagnostic and surgical procedures involving the posterior fossa. The findings reveal notable diversity in AICA origin, course, and diameter, with implications for imaging interpretation and clinical management, particularly in cases of vascular pathology such as infarction or aneurysm.